This invention relates to a blind fastener and is particularly directed to a blind fastener comprised of a rivet and cooperating pin which is threaded into the rivet, the rivet and pin being so constructed that when the pin is threaded into the rivet against weakened zones therein, a blind head is formed on the rivet, locking the fastener in position.
Blind fasteners are often required for rapid repair of damaged aircraft. Presently available blind fasteners for this purpose have a limited grip range with respect to the length of the rivet, and hence, a large inventory of different length and grip-size rivets are required to be maintained in order to repair damaged components of aircraft at the site.
A variety of blind fasteners are known in the art for fastening together two sheets through an aperture in both sheets. Such blind fasteners generally employ a pin within a sleeve. The pin is adapted to be engaged by a tool which pulls the pin partially through the sleeve, forcing part of the sleeve outwardly to form a bulge abutting the sheet and preventing movement of the sheets against the bulge. Such pins are designed to break off upon the application of sufficient pulling force thereto.
An example of the above prior art type of blind fastener is disclosed in U.S. Pat. No. 4,046,053 to Alvi, et al. The fastener of Alvi is constructed of a very hard material, such as carbon steel. In this fastener, the inner pin is particularly designed to actually collapse and shrink as it is subjected to a pulling force. In order to shrink, the rivet must be subjected to a very high force requiring that the rivet be made of steel or such other material. Thus, the fastener of this patent is not adapted for use with composite rivets or with composite sheets comprised of an organic polymeric material because the high forces required to install such rivets would tend to damage both the sheets and the rivets.
It is an object of the present invention to provide a novel blind fastener comprised of a rivet, preferably constructed of non-metallic material, having an internally threaded bore and a threaded pin for threadable engagement with the rivet and arranged and constructed to form a blind head on the rivet when the pin is threaded into the rivet against zones of weakness provided in the rivet wall.
Another object of the invention is the provision of an improved multigrip fastener of the above type, which is adapted to grip over a wide range of fastener length, to thereby permit rapid fastening of components of varying thickness, particularly damaged aircraft components.
Yet another object is the provision of a blind fastener of the above type which is of simple construction and does not require the use of high force to install the fastener.